I can't hollow out a skull!!! Who can???

[Roxy]

I'm trying to hollow out a solid .STL file of a skull. What I'm hoping to do is make it into a little container where the very top comes off and there is a small container in the open area where the brain would be. l can make it work just fine with OpenScad except it won't render. I can see what I'm doing is OK, but OpenScad can't complete the job. Check this out:

Skull_Coin_Box.jpg

I'm trying to use the attached Skull.STL file as a starting point. (And of course, there is a matching Mandible.stl that goes with it! My Skull Coin Box is going to need teeth!)

Actually... The Forum is having problems with .STL files again. The file came from here: www.thingiverse.com/thing:43591/#files But I had one uploaded as 'Test.stl' and it is attached.

What I'm hoping is somebody can tell me how to use Rhino or MeshLab or Blender to hollow out the skull. If I can just get it hollowed, I can slice it in two pieces and print up the little dowels to align the top. I've looked at all 3 of those programs, but I'm not even sure they can do what I want. And if they can, this is a pretty advanced topic to start with when trying to learn those programs.